1. Field of the Invention
The present invention relates to systems and methods that are used to monitor and test the integrity of optical fibers between points. More particularly, the present invention relates to systems and methods of monitoring a set pair of optical fibers that lead to specific customer facility from the central office of a telecommunications provider.
2. Description of the Prior Art
There are many applications that utilize an optical fiber network to establish optical communications between a host digital terminal (HDT) at a central office and an optical network unit (ONU) at a remote location. Since a central office serves as the point of origin for the optical fibers in the optical fiber network, equipment is used at the central office to organize various optical fibers in the optical fiber network. In certain optical networks, the optical fibers at the central office are connected to dedicated pieces of equipment, such as optical signal transmitters, that serve only one purpose. If the optical fibers are to be connected to another piece of equipment, such as test equipment, the optical fibers must be manually connected to that new piece of equipment.
In more versatile applications, optical fibers are terminated at fiber administration systems at the central office. Fiber administration systems enable many different types of equipment to be connected to the optical fibers without having to reroute the optical fibers from their point of termination.
In many fiber administration systems, as the optical fibers in a network enter the central office, they are directed into an optical distribution frame where the individual optical fibers are terminated in an organized manner. Such fiber administration systems are exemplified by the LGX(copyright) fiber administration system which is currently manufactured by Lucent Technologies of Murray Hill, N.J., the assignee herein.
Each optical distribution frame located at the central office typically defines a plurality of bays, wherein each bay houses several different type of dedicated equipment shelves, such as fiber distribution shelves. On each of the fiber distribution shelves are optical connection ports that receive the ends of all of the individual optical fibers that enter the central office and are contained within the optical fiber network. By terminating each optical fiber at an optical connection port on one of the different fiber distribution shelves, the location of each optical fiber becomes known within the overall assembly. Once terminated at a known address on one of the fiber distribution shelves, each optical fiber can be selectively coupled to equipment on other shelves of the fiber administration system or other optical equipment located at the central office. As a result, the optical signals sent along each optical fiber can be selectively controlled.
At the opposite end of the various optical fibers are the customers of the telecommunications provider. With customers that have smaller scale telecommunications needs, the optical signals transmitted on the optical fiber network are converted to electrical signals, prior to the customer""s premises in a traditional manner. As such, the entire optical network is controlled and maintained by the telecommunications provider. However, with customers that have large scale telecommunication requirements, it is not uncommon for the telecommunications provider to run a pair of optical fibers from the optical network directly into the customer premises. One of the optical fibers transmits signals from the telecommunications provider to the customer and the other optical fiber transmits signals from the customer to the telecommunications provider.
With customers that receive optical fiber pairs from their telecommunications provider, all incoming and outgoing transmissions are directed through these optical fibers. Accordingly, to disconnect either of these optical fibers is to completely disrupt the telecommunications service to that customer.
When a customer reports trouble with a telecommunications transmissions, the problem can be either related to the optical fibers owned by the telecommunications provider or the telecommunications equipment owned by the customer. Since the optical fiber leading to the customer premises cannot be disconnected, it is difficult to pinpoint whether a problem is contained in the telecommunication provider""s equipment of the customer""s equipment. The result is that a technician from the telecommunications provider must be dispatched to the customer""s premises and time consuming manual tests must be conducted to locate the exact point of the problem.
A need therefore exists for a system and method, whereby the integrity of an optical fiber pair leading to specific customer premises can be monitored and tested in a remote, automated procedure.
The present invention is a system and method of monitoring and testing the integrity of a pair of optical fibers that are received by a specific customer facility through the optical fiber network of a telecommunications provider. In one exemplary embodiment, the system contains an optical transmission module, a monitoring module, and two wavelength division multiplexing modules. The optical transmission module, the monitoring module and the first wavelength division multiplexing module are located at the telecommunication provider""s facility. The second wavelength division multiplexing module is located at the customer""s facility. The optical transmission module at the telecommunications provider""s central office introduces test signals onto the first dedicated optical fiber of a customer facility, using the first wavelength division multiplexing module. The test signal travels to the customer facility through the optical fiber network. At the customer facility, the test signal is looped onto the second dedicated optical fiber using the second wavelength division multiplexing module. The test signal then returns to the telecommunication provider""s facility, wherein the test signal is received by the monitor module, the optical transmission module and the monitor module are connected to a common controller. That controller can therefore compare the outgoing test signal to the incoming test signal and can calculate the integrity of the optical fibers that travel to and from that customer facility.